Reciprocating fuel pumps

ABSTRACT

Improved system for supplying fuel and oil to two-cycle internal combustion engines including a simple and reliable fuel-oil injector pump which mixes the fluids in a desired ratio from separate tanks. Means for automatically shutting off fuel flow upon loss of oil are provided. Crankcase scavenging pressure assists oil pumping. The injector pump continuously circulates fuel through the fuel tank to avoid vapor lock. Several arrangements for properly correlating the injector pumping rate with engine air flow are disclosed. An improved injection nozzle utilizing an elastomeric band is disclosed. A system for supplying dual cylinders from the same injector pump is disclosed.

United States Patent 1 1 Ulbing 4] RECIPROCATING FUEL PUMPS 75 Inventor:Otmar M. Ulbing,.Lisle, NY.

[73] Assignee: Borg-Warner Corporation, Chicago,

Ill.

[22] Filed: June 1, 1971 [21] Appl. No.1 153,460

Related US. Application Data [63] Continuation of Ser. No. 786,233, Dec.23, 1968,

abandoned.

[52] US. Cl. 417/469, 417/496, 417/497,

[51] Int. Cl. F04b 7/04 [58] Field of Search..... 417/490494, 496,499,498

[56] References Cited 1 UNITED STATES PATENTS 1,854,009 I 4/1932Wilkinson 417/498 1,917,169 7/1933 Ulgers et al.... 417/490 2,551,0535/1951 Rogers 417/565 2,576,451 11/1951 Dickson et a1 417/498 June 19,1973 2,740,667 4/1956 Dickson et a1 417/494 2,676,544 4/1954 Schauer417/490 2,890,657 6/1959 May et a1..... 417/494 2,969,738 l/196l Ulbing417/494 Primary ExizminerWilliam L. Freeh Attorney-Richard G. Stephens[57] ABSTRACT Improved system for supplying fuel and oil to two-cycleinternal combustion engines including a simple and re liable fuel-oilinjector pump which mixes the fluids in a desired ratio from separatetanks. Means for automatically shutting off fuel flow upon loss of oilare provided Crankcase scavenging pressure assists oil pumping. Theinjector pump continuously circulates fuel through the fuel tank toavoid vapor lock. Several arrangements for properly correlating theinjector pump-' ing rate with engine air flow are disclosed. An improvedinjection nozzle utilizing an elastomeric band is disclosed. A systemfor supplying dual cylinders from the same injector pump is disclosed.

24 Claims, 18 Drawing Figures Patented June 19; 1973 10 Sheets-Sheet 4MM M W Patented June 19, 1973 10 Sheets-Sheet 5 Patented June 19, 197310 Sheets-Sheet 6 Patented June 19, 1973 3,740,172

10 Sheets-Sheet 7 FIG. 3c

FIG. 3e

Patented June 19, 1973 -10 Sheets-Sheet 8 Patented Jam-19, 19133,740,172

10 Sheets-Sheet 9 Patented June 19, 1973 10 Sheets-Sheet 10 Am OERECIPROCATING FUEL PUMPS This application is a continuation of my priorcopending application Ser. No. 786,233 filed Dec. 23, 1968 and nowabandoned.

This invention relates to two-cycle gasoline engines, to fuel andlubrication injection and control systems for the same, and variousfeatures of the invention have application to other types of engines andeven various nonengine applications.

A wide variety of machines, such as snowmobiles, motorcycles and variousother devices utilize two-cycle gasoline engines, ordinarily because ofthe lower cost per horsepower and lesser weight per horsepower of suchengines, and their lower cost is the primary reason why two-cycleengines are preferred to four-cycle engines in many such applications.Despite their mentioned advantages, two-cycle engines have not met withfavor in a number of applications due to the necessity of providing agasoline-oil mixture in order to insure lubrication of the enginecrankcase bearings and the cylinder walls. Providing a mixture ofgasoline and oil in the proper ratio is troublesome and time-consuming,and many two-cycle engines have been ruined because the ratio of themixture has been wrong. While the calculation of proper amounts of oiland proper amounts of fuel to provide a desired ratio involves onlyelementary mathematics and a modicum of care, experience has shown thatin the ordinary applications of many two-cycle engines the mistakes ofunskilled or careless persons result in improper ratios frequently beingused, often to the detriment of the engine. It is one object of ing highheat conditions. Another object of the invention is to provide animproved fuel-oil injection system which insures better starting of atwo-cycle engine in cold weather when oil viscosity may be rather high.

While a number of two-cycle engine systems utilizing carburetion havebeen deemed satisfactory for constant load or other specificload-applications, they have been disadvantageous in not beingcontrollable over a very wide range of speeds. It is a further object ofthe invention to provide a two-cycle engine system which can runsmoothly, under varying load conditions, over a greater range of speeds.The present invention also allows a two-cycle engine to provide higherpower output at a given speed, both at low and high speeds, and allowsthe engine to accelerate and decelerate without the delay whichaccompanies some carburetion systhe present invention to provide atwo-cycle engine system in which oil and gasoline may be supplied to tworespective tanks with no pre-mixing being required and in which meansare provided to automatically mix the oil and gasoline in the properratio as they are used, so that no pre-mixing is required, and so thatthe proper mixture or ratio is always provided, no matter whether theengine is running fast or slow. In some applications different mixtureratios are desirable at different engine speed and load conditions, andit is another object of the invention to provide a system in whichmixture ratio may be arranged to vary automatically with the flow rateof the fuel-oil mixture supplied to the engine.

Cost is a major factor in many of the applications for which two-cycleengines are utilized, and most, if not all, prior two-cycle engines haveutilized carburetors rather than fuel injection systems, due to the highcost and complexity of prior fuel injection systems. However,carburetors have a number of disadvantages which are overcome by thepresent invention. For example, carburetors are difficult to adjust,even by skilled mechanics sometimes, and they frequently requirere-adjustment. It is another object of the present invention to providea fuel-oil injection system for twocycle engines which requires nocomplex adjustment procedureand which does not require periodicreadjustment. Carburetors also become clogged frequently, due tothesmall passages necessarily included in them and the low pressures whichthey develop, and one object of the present invention is to provide afuel-oil injection system for a two-cycle engine which is lesssusceptible to clogging. Carburetion systems frequently are plagued byvapor lock problems, and a further object of the invention is to providea fuel-oil injection system which overcomes vapor lock problems, whichotherwise often occur in two-cycle engine systems durterns.

In ordinary two-cycle engine systems involving carburetion, little or nofuel-oil mixture is supplied to the engine intake manifold, and hencelittle or not engine lubrication is provided, unless the carburetorthrottle plate is open, i.e., unless the accelerator pedal is depressed,for example, in a snowmobile, even though the snowmobile may betraveling at ahigh speed and the engine turning at a high speed, withthe result that many two-cycle engines have been ruined for lack oflubrication when a snowmobile, for example, coasts down a long, steephill with the engine running slowly and braking the snowmobile. Mosttwo-cycle engines can operate in such an overrunning condition for onlyperhaps 60 to seconds without seriously damaging the engine. It isanother important object of the invention toprovide a two-cycle enginesystem wherein suc operation is automatically prevented.

If a two-cycle engine is operated for any substantial length of timewithout lubrication, it rapidly will be damaged, as just mentioned. Ifpremixing of gasoline and oil is to be avoided and gasoline and oil areinstalled in separate tanks without the need for measuring preciseamounts of each, and if the gasoline and oil are automatically dispensedfrom the two tanks with theproper ratio, it will be apparent that onetank well may become emptied before the other, and that if the oilsupply became depleted before the gasoline supply, continued running ofthe engine might seriously damage the engine. Thus it is anotherimportant object of the invention to provide a two-cycle fuel-oilinjection system in which the engine will be automatically shut off ifthe oil supply fails while the engine is running, so that damage to theengine will not result. The invention also includes a novel, inexpensiveand reliable injection nozzle assembly which efficiently atomizes themixture supplied by the injector of the invention. Attending each of theaforementioned objects is the very important object of providing a fuelinjection system for a two-cycle engine which is inexpensive, compact,and reliable, having no delicate parts whichare subject to failure ormisadjustment. Further objects of the inven tion are to provide a fuelinjection pump wherein lesser pressures are built up across .the pumppiston for a given pumping flow rate so that less precisepistoncyclinder tolerance is required, and a pump in which delivery perstroke is substantially independent of pump speed, supply pressure, andcheck valve loading.'

Two-cylinder two-cycle engines often utilize two carburetors rather thana single carburetor inorder to provide greater power output. If onecarburetor fails such engines frequently continue to run on onecylinder, and the lack of lubrication then experienced by the cylinderfed by the failed carburetor may cause considerable damage. It isanother object of the invention to provide a fuel-oil injection systemfor a two-cylinder two-cycle engine which prevents the possibility ofsuch damage.

Other objects of the invention will in part be obvious and will, inpart,appear hereinafter.

The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts, which will beexemplified in the constructions hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the inventionreference should be had to the following detailed description taken inconnection with the accompanying drawings, in which:

FIG. 1 is a side view of a two-cycle engine showing portions of a systemconstructed in accordance with the present invention.

FIG. 2 is a cross-section view of one form of fuel-oil injector pumpconstructed in accordance with the present invention, with additionalparts of a fuel and oil control system shown schematically.

FIG. 2a is a view taken at lines 2-2 in FIG. 2.

FIG. 2b is a view taken at lines 3in FIG. 2 with plug 64b removed.

FIG. 2c is a diagrammatic view useful in illustrating the operation ofthe pump of FIGS. 2, 2a and 2b.

FIG. 3 is a cross-section view taken at lines 44 in FIG. 3b through afurther form of fuel-oil injection pump.

.FIG. 3a is a view taken at lines 55 in FIG. 3 with piston 161 andsprings 133 and 162 removed.

FIG. 3b is a view taken at lines 66 in FIG. 3a.

FIG. 30 is a view taken at lines 77 in FIG. 3.

FIG. 3d ia view taken at lines 8-8 in FIG. 3.

FIG. 3e shows a portion of an injector pump of the type shown in FIGS. 3and 3a-3d connected to be controlled by control apparatus illustratedschematically.

FIG. 4 is a side view of the engine showing one manner in which theinjector pump of the present invention may be arranged to be operatedfrom the cranksahft (or other shaft) of an engine.

FIG. 5a is a front view of the air intake duct of the engine system ofFIG. 1.

FIG. 5b is a side view of the air intake duct of the engine system ofFIG. 1.

FIG. 6 is a side view of a portion of the system of FIG. 1 illustratingthe atomizing injector nozzle of the present invention.

FIG. 6a is an enlarged isometric view of a port of the nozzle assemblyof FIG. 6.

FIG. 6b is a view taken at lines 99 in FIG. 6.

FIG. 7 is'a view partially cutaway illustrating use of an injector pumpto supply both cylinders of a dual cylinder two-cycle engine.

Referring now to FIG. 1, a known type of two-cycle engine 10 is shown asincluding an externally-finned cylinder 11 having a single piston (notshown) inside, spark plug 13 and crankcase 14. FIG. 1 is drawn toresemblethe basic structure of a Series SA 290 Model 297-68 engine,(Ser. No. 5529098) manufactured by Sachs GmbH in Germany andcommercially available in the United States. Engine 10 is provided withan air intake duct or chamber 15 which communicates directly with theinput duct (not shown in FIG. 1)

through which fuel (and oil) are admitted to the crankcase of engine 10.Intake chamber 15 (or manifold in the case of multicylinder engines)includes an open end to admit air and includes an adjustable throttleplate (not shown in FIG. 1), the adjustment of which controls the airflow through passage 15. The throttle plate corresponds in one basicprinciple to the throttle plate used to choke ordinary carburetedengines. A

fuel-mixture injection nozzle assembly 18 includes a nozzle whichextends into intake chamber 15. A fueloil mixture is supplied to thenozzle of assembly 18 via tubing 18a from injector pump 12. Variouspreferred details of the nozzle 18 assembly will be further explained inconnection with FIG. 6. Engine 10 is a common type of two-cycle engineof the crankcasescavenged type, having a hermetically-sealed crankcasein which the pressure changes as the piston rises and descends. It willbecome apparent as the. description proceeds that the invention isapplicable as well to two-cycle engines of the type which use a separatescavenging fan or pump. Furthermore, while engine 10 is shown as a typewherein gasoline and oil are applied as a mixture to an intake chamber,it will become apparent that many aspects of the invention areapplicable as well to two-cycle engines of the autolube" type whereinoil is not mixed with the gasoline prior to its introduction into theengine, but instead pumped through suitable conduits to specific bearingor other desired lubrication points within the engine.

FIGS. 2, 2a and 2b illustrate one form of injector pump constructed inaccordance with the present invention, and FIG. 2c is a porting diagramuseful in illustrating the operation of that fuel injector, whichutilizes a number of the principles of the pump illustrated in my priorUS. Pat. No. 2,969,738. The fuel injector comprises a central casting orhousing 20 preferably of aluminum having a rear head 21 and a front head22 bolted thereto, with suitable gaskets 21a and 21b therebetween. Fourmounting holes 20f, 20f (FIG. 2) are provided through casting 20 tomount the injector pump on the'engine crankcase. Three mounting holes20g, 20g (FIG. 2b) are provided to bolt each head to central casting 20.Shaft 23 driven by the engine crankshaft through pulley 24 and a timingbelt 25 (FIG. 1) is journalled in casting 20 and extends through oilseal 26 (FIG. 2a) in one wall of housing 20 and carries eccentric cam 27which is disposed within hollow chamber 28. A domed circular cup 23a(FIG. 2a) pressfitted into one side of casting 20 closes the side of thecasting and axiallylocates shaft 23. Casting 20 also includes alongitudinally-extending bore 29 which extends into chamber 28.Generally cylindrical sleeve 29a is prefitted into place in bore 29, andpiston 30 is situated within sleeve 29a, which is provided with aplurality of ports, as will be described. Control rod 31 is rotatablyjournalled in rear head 21 and secured against axial movement by meansof snap rings 32a, 32b which engage circumferential slots in rod 31.U-shaped return spring means 33 interconnects piston 30 and control rod31, the forked ends of spring 33 engaging pins 34 and 35 which' extendthrough respective ends of rod 31 and piston 30. As the enginecrankshaft rotates pulley 24 and shaft 23, eccentric cam 27 will be seento urge piston 30 rightwardly against the force of spring means 33during a portion of each revolution of cam 27, and the spring means willreturn piston 30 leftwardly during another portion of each revolution,and hence piston will reciprocate back and forth a predetermineddistance within bore 29 during each cam revolution. has much as controlrod 31 is rotatably journalled in head 21 and piston 30 is rotatablewithin bore 29, angular rotation of control rod 31 will be seen to actthrough spring means 33 to similarly angularly rotate piston 30.

Cylindrical sleeve 29a has a plurality of ports 34-37 and piston 30 isprovided with a plurality of external grooves 38, 39 which extendpartially around the periphery of piston 30, and hence angular rotationof piston 30 about longitudinal axis x--x by means of control rod 31serves to angularly position grooves 38, 39 with respect to ports 3436.Ports 34-37 are each shown as comprising a slot which extends partiallyaround sleeve 290, with each slot having a uniform width measured in theaxial direction of sleeve 29a. Oil intake port 34 in sleeve 29a connectsto hollow chamber 28 through passage 41, an piston 30. slot milled insleeve 29a. Oil outlet port 35 connects through passage 42a to checkvalve 50 situated within passage 42b, which extends to mixing chamber 43provided within front head 22. A ball 42c plugs the end of passage 42a.Fuel (gasoline) intake port 36 connects via passage 44, alongitudinally-extending slot milled in sleeve 29a, to fuel inletchamber 64 and thence via fuel supply lines a, 45b

to fuel tank 46, and fuel outlet port 37 connects via passages 47a, 47band check valve 51 to mixing chamber 43.

Each of the grooves 38, 39 on piston 30 comprises a V-shaped groovemilled on the periphery of cylindrical piston 30, with the depth of eachV-groove equal to ap proximately half the diameter of piston 30, so thatthe apices of each V-groove are spaced apart approximately 180 degreesfrom each other around piston 30. Piston 30 is shown rotated 90 degreesfrom its ordinary operating range of positions in order to afford abetter view of V-grooves 38 and 39. Ports 34-37 in sleeve 29a are eachshown extending perpendicularly to axis x-x. The relationship ofV-groove 38 to oil intake and outlet ports 34 and 35, and the similarrelationship of V- groove 39 to fuel intake and outlet ports 36 and 37,are better illustrated by the geometric diagram of FIG. 2c wherein theoutside surface of piston 30 and the inside surface of sleeve 29a areshown developed, or unrolled, and superimposed on each other. The use ofa v-shaped milling tool having straight sides will be recognized toprovide grooves on cylindrical sleeve 29a of the nature shown at 38 and39 in FIG. 20.

FIG. 2c illustrates in solid lines a condition where pis ton 30 is atits leftward limit of travel and where piston 30 has been rotated bycontrol rod 31 to an angular position to provide a minimum or a very lowpumping rate. V-groove 38 will be seen to communicate with orsubstantially register with oil intake port 34, and V- groove 39 tosubstantially register with fuel intake port 36, while oil outlet port35 and fuel outlet port 37 will be seen to be blocked. Rightward travelof piston 30 in FIG. 2 is represented by rightward movement of V-grooves 38 and 39 relative to ports 34-37 in FIG. 2c. As piston 30 movesrightwardly in FIG. 2c, V-groove 38 will be seen to register less andless with port 34, and nearer and nearer toward a position where it willregister with port 35. The shape of groove 38 and the loca tions ofports 34 and 35 are established so that groove 38, over its entirestroke, will communicate with at least one or the other of ports 34, 35,and at all angular positions of piston 30, groove 38 will communicatewith both ports 34 and 35 during a certain portion of each stroke.

With piston 30 in the angular position shown in solid lines in FIG. 20,it will be seen that groove 38 will register with port 34 during most ofthe piston stroke (the total length of which is indicated by distance sin FIG. 20) and will register with port 35 only during a very smallterminal portion of the rightward stroke. If piston 30 is rotated withinbore 29, however, such as to a me dium position indicated by groove 38in dashed lines at 38a in FIG. 30, it will be seen that groove 38 willbe cut off from inlet port 34 earlier during the rightward stroke andwill register with outlet port 35 during a substantial portion of thestroke. If piston 30 is further rotated within bore 29, so that groove38 can be represented at 38b in FIG. 20, it will be seen that groov 38will cutoff from inlet port 34 and communicate with outlet port 35 veryearly during the rightward stroke. Thus by angularly positioning piston30 within bore 29 by means of control rod 31, one may control therelative times during a stroke during which the two ports 34 and 35communicate with movable piston groove 38. Groove 39 operates relativeto ports 36 and 37 in precisely the same way that groove 38 operatesrelative to ports 34 and 35. Inasmuch as grooves 38 and 39 are fixedlyspaced relative to each other on piston 30, and inasmuch as ports 34-37are all fixedly spaced relative to each other in bore 29, it will beseen that the opening and closing of inlet and outlet ports arepermanently synchronized with each other, need no adjustment and cannotget out of adjustment.

Referring back now to FIG. 2, it will be seen that piston 30 includes acentral longitudinal bore 55 and a hollowed-out right end portion 56which communicates with the portion of bore 29 on the righthand side ofpiston 30, to provide chamber 60. Oil piston 61 fits within bore 55 andinner coil spring 62 urges oil piston 61 rightwardly from piston 30.Chamber is shown as in-cluding a valve seat 63 against which end 61a ofpiston 61 is seated by the force of spring 62 to close off chamber 60from chamber 64. In many embodiments of the invention valve 61a-63 maybe omitted, and piston 61 may, if desired, be rigidly affixed to theright end of chamber 60, and then inner coil spring 62 is not re:quired. Even if no valve or passage is provided at 64, I prefer however,not to rigidly affix the right end of piston 61, and to allow spring 62to urge piston 61 rightwardly against the closed right end of chamber60, as allowing piston 61 to float rather than permanently affixing itto chamber 60 obviates precision alignmen problems.

To understand the operation of the fuel injector of FIG. 2, firstas-sume with piston 30 at its left limit of travel that chamber 28,passage 41, oil intake port 34,

V-groove 38 and chamber 65 (the portion of bore 55 to the left of piston61) are all filled with oil. As eccentric cam 27 urges piston 30rightwardly, piston 61 will be seen to expel oil out from chamber 65,and since V groove 38 initially registers only with inlet port 34, oilinitially will be pumped back through port 34 into chamber 28. Therightward excursion of piston 30 will be seen to provide a suction inchamber 28, thereby accelerating the oil flow from port 34 to chamber28.

port 34 will be closed, so that oil will be expelled only through oiloutlet port 35, past check valve 50 to mixing chamber 43. The timesduring the rightward stroke during which port 35 is opened and port 34is closed are determined, it will be recalled, by the angular positionof piston30.

With fuel supply line 45a connected to fuel inlet port 36, and withV-groove 39 communicating with chamber 60, it will be seen that fuelwill be ex-pelled from chamber 60 back through groove 39 toward the fuelsupply tank 46 during an initial portion of the rightward stroke ofpiston 30, and then expelled through fuel outlet port 37 past checkvalve 51 to mixing chamber 43 during aterminal portion of the rightwardstroke. Because of the fixed relationship shown between grooves 38, 39and ports 34-37, return pumping of oil back through inlet port 34 willoccur for the same portion of the stroke during which fuel is pumpedback into supply line 44, and forward pumping of oil past check valve 50will occur throughout the same portion of the stroke that fuel is pumpedpast check valve 51, and by rotation of piston 30 by control rod 31, therelative amounts of return pumping and forward pumping which occur on agiven stroke can be controlled for both fluids. Inasmuch as oil outletport 35 and fuel outlet port 37 are opened for the same portion of eachrightward stroke of piston 30, it will be seen that the relative amountsof the two fluids which are pumped during each rightward stroke dependssolely upon the ratio of the effective areas of the two pistons, theeffective area A of oil piston 61 being 11-11 where d is the diameter ofpiston 61, and the effective area A, of fuel piston 30 being 1r(d -dwhere d is the diameter of piston 30 or bore 29. If A, is arranged to betimes A for example, it will be seen that 25 times as much fuel as oilwill be pumped on a given rightward stroke. With the relative amounts offuel and oil fixed by the relative effective piston areas, it will beseen that a mixture having a desired fuel-oil ratio always will beobtained, irrespective of the amounts of each fluid pumped during agiven stroke.

It will be apparent at this point that by proper spacing of the portsand the V-grooves one may provide one extreme angular position of pistonwhich will result in inlet ports 34 and 36 being cutoff and outlet ports35 and 37 being opened very near the beginning of the rightward stroke,thereby to provide maximum pumping, and one may provide another extremeangular position which will result in inlet ports 34 and 36 being cutoffand outlet ports 35 and 37 being opened at or near the end of therightward stroke, so that little or no fluids will be pumped. It isimportant, however, that all angular positions of piston 30 provide atleast some slight overlap between the opening of the outlet ports andthe closure of the inlet ports, in order that blockage of fluid notdamage the injector. While FIGS. 2 and 2c illustrate a pump valvingarrangement wherein V- grooves have been provided on piston 30, toprovide openings having an edge which varies in longitudinal position asa function of piston angular position, and wherein the cylindricalsleeve has straight slots, each having an edge which does not vary inlongitudinal position as a function of its angular position it willbecome apparent that equivalent valving may be provided with othercombinations of shapes of grooves and slots. For example, it will beapparent that equivalent operation may be effected through a simplereversal of parts, providing piston grooves of unvarying width andsleeve slots having edges whose longitudinal positions vary with angularposition. Also, it will become apparent upon reflection that it isunecessary that either a port or its cooperating groove have an edgewhich does not vary longitudinally with angular position, and that bothmay vary, though at different rates, to provide equivalent overalloperation. The specific valving system described in detail is preferred,however, inasmuch as it may be provided accurately and inexpensivelyusing only simple machining operations. Both grooves 38 and 39 may bemilled simultaneously on piston 30 using a pair of spaced V-shapedmilling cutters, and pairs of ports may be milled simultaneously insleeve 29a using straight-sided milling cutters.

In the specific porting system shown both inlet ports open and close atthe same time and both outlet ports open and close at the same time,irrespective of the angular position of piston 30 in sleeve 29a. It ispossible, however, to vary the relationship between the ports andgrooves so that the time at which the fuel inlet port closes and thetime at which the fuel outlet port opens are not always the same timesat which the oil inlet port closes and the oil outlet port opens, butrather vary relative to each other in accordance with the angularposition of piston 30. For example, if the fuel inlet and outlet portsare given a slight axial cant, as indicated in FIG. 20 at 36a and 37a,while oil ports 34 and 35 have no such cant, it will be seen that thefuel system will switch from return pumping to forward pumping earlierduring each pumping stroke than when the oil system switches, with theamount by which fuel forward pumping precedes oil forward pumpingvarying with the angular position of piston 30, so that fuel ports ofthe nature shown at 36a and 37a will automatically provide a thinnermixture (i.e., greater ratio of fuel to oil) as the pump flow rateincreases. Canting the fuel ports in an opposite direction would providea richer mixture as pump flow rate increases. Provision of a thinnermixture as flow rate increases obviously may be provided by giving oilports 34 and 35 a counterclockwise cant instead of giving fuel ports 36and 37 the clockwise cant shown at 36a and 37a, and provision of aclockwise cant at ports 34 and 35 would provide a richer mixture atgreater flow rates. It should be apparent at this point that both theoil ports and fuel ports may be canted, in either the same or oppositedirections, and that the relative angular relationship between them willdetermine the sense and the amount by which the mixture ratio changes asthe flow rate varies, and it will also be apparent that equivalentoperation may be effected by suitably shaping the piston grooves insteadof or in addition to canting the ports. It is not necessary that cantedpairs of ports always utilize straight-sided ports, and if desiredcanted curved ports may be provided in order that mixture ratio varywith pump flow rate in a desired non-linear manner. Irrespective ofwhether pump 12 provides a fixed mixture at all flow rates or a ratiowhich varies with pump flow rate, it will be appreciated that the ratioat a given rate is inherently built into the piston-cylinder portgeometry and cannot get out of adjustment.

A number of prior art pumps using angularlyadjustable pistons forvariable metering of a fluid provide only an inlet port, rather thanboth inlet and outlet ports, so that their pump chambers are in constantcommunication with their outlet check valves, and forward pumping pasttheir check valves occurs as te inlet port is closed off to preventreturn flow. If the fluid supply has positive pressure, it will be seenthat the check valve in such prior systems must be loaded to at leastthe same pressure in order to prevent forward pumping prior to completeclosure of the inlet port. And even if the fluid supply is notpressurized, it should be understood that the pressure in the prior artpump chambers necessarily builds up prior to complete closure of theirinlet ports, in amounts dependent upon the pump speed and the amount ofrestriction to return flow between the pump chamber and the fluidsupply, with the amount of restriction increasing from a basic amount tocomplete blockage as the inlet port is gradually closed off. If forwardpumping is not to occur prior to complete closure of the inlet port, thecheck valve must be loaded to the highest such pressure which may occurprior to inlet port closure. The heavier check valve loading necessarilyresults in higher pressures in the pump chamber, thereby requiring amore precise piston-cylinder fit. [the pump of the present inventionforward-pumping cannot occur prior to opening of an outlet port,irrespective of whether the supply is pressurized, and hence the instantat which forward pumpig begins during a pumping stroke remainssubstantially independent of pump speed and outlet check valve loading.

Chamber 2 8 in FIG. 2 is connected to oil supply tank 75 through a checkvalve 68. As piston 30 starts leftwardly on its return stroke, thepressure in chamber 28 will be seen to increase positively and to tendto continue to increase during further return travle, to a maximum valuedetermined by the setting of check valve 68. Simultaneously, upon thereturn of piston 30, oil outlet check valve 50 prevents reverse flow ofoil from mixing chamber 43, and hence an increasing partial vacuum willbe built up at port 35 and within chamber 65 and V-groove 38. Whenpiston 30 has returned sufficiently far for V-groove 38 to register withinlet port 34, it will be seen that the positive pressure in chamber 28and the partial vacuum in V-groove 38 and chamber 65 will both actcumulatively, to force oil from chamber 28 through port 34 to fillchamber 65 very quickly during the latter portion of the return stroke.Similarly fuel inlet port 36 connects to supply tank 46 through checkvalve 74, and as fuel is pumped toward tank 46 during the initialportion of the rightward stroke of piston 30, a positive pressueapproaching the loading of check valve 74 will build up in line 45abetween port 36 and check valve 74. The initial portion ofthe returnstroke also creates a partial vacuum at port 37 and in chamber 60 andV-groove 39, and when V-groove 39 registers with port 36 near the end ofthe return stroke,- the combination of the positive pressure and partialvacuum result in quick filling of chamber 60. Chambers 65 and 60 must befilled very rapidly, during a small portion of he injector cycle whenthe engine is running fast with an appreciable load, and the combinationof pressure and vacuum which serves to fill them rapidly is an importantfeature of the invention.

Mixing chamber 43 in head 22 by means of a threaded connection at 43avia tubing 180 (FIG. 1) to an injection nozzle in assembly 18 whichextends into the intake duct of the engine. In applying the invention toautolube type two-cycle engines, it will be apparent that the twopassages leading from check valves 50 and 51 should not lead to a mixingchamber, but instead that the fuel passage alone should lead to theinjection nozzle and the oilpassage'should leadto the lubrication pointsin the engine.

FIG. 2 an optional modification is illustrated wherein a ball checkvalve76 is shown interconnecting chamber and chamber 60, and if such a checkvalve is provided, oil outlet port 35, passage 42a and check valve 50may be eliminated. During the rightward piston stroke with such anarrangement, it will be seen that oil pressure will build up in chamber65 as soon as oil inlet port 34 is cut off, and the oil will] passthrough check valve 76 and be mixed with the fuel in chamber 60, and afuel-oil mixture will be pumped out of chamber 60 during each stroke.

In FIG. I the fuel line from fuel 46 is connected to chamber 64 withwhich valve 61a-63 also communicates. It will be seen that the vacuumcreated in chamber 60 during the return stroke produces a differentialpressure across valve 61a-63 which may be arranged, by selection of thevalve 61a area, to overcome spring 62 and urge piston 61 leftwardlyduring each return stroke, so that chamber 60 may be filled from chamber64 via valve 61a-63 as well as through port 36. This additional meansfor quickly filling chamber 60 is wholly unnecessary in mostapplications of the invention, however. The use of valve6la-63 doesprovide a useful safety feature, however. In FIG. 2 the fuel pressure inchamber 60 will be seen to act on piston rod 61 tending to move itleftwardly against a combined force applied to piston 61 by spring 62and the oil pressure in chamber 65, and during normal operation therighward pressures on piston 61 maintain its valving end 61a tightlyseated on valve seat 63. If the oil supply in tank should run out,however, the loss of oil pressure in chamber 65 lessens the rightward.force on piston 61, whereupon the fuel pressure in chamber 60 overcomesthe force of spring 62, moving valve end 61a off of valve seat 63. Fuelin chamber 60 than will be expelled through valve 6ll63 into chamber 64rather than being pumped out through port 37, and hence the en gine willstall. Valve 61a-63 may connect to a conduit which merely spills thegasoline on the ground, if desired, but preferably it is connected asshown to return to chamber 64.

In order to insure the transfer of low viscosity oil from tank 75 to theinjector during; cold weather, a substantial scavenging pressure (e.g.10-15 psig) from the engine crankcase is applied via check valve 77 tooil tank 75, which is closed with a pressure-type cap. Oil tank 75connects to oil chamber 28 of the injector through a lightly-loadedcheck valve 69 which allows easy flow of oil to chamber 28 during thepumping stroke of injector piston 30, but shunt-connectedoppositely-oriented check valve 68 allows pressure to build up inchamber 28 during a portion of the return stroke. It may be noted thatthe creation of such pressure in chamber 28 during the return strokedoes require the use of a stronger return spring at 33.

With positive pressure applied to the oil supply in the mannermentioned, a safety interlock" of the same nature as that described inconnection with valve 61a-63 may be provided without the use of such avalve. With the oiltank 75 so pressurized, as soon as all the oil isused up air under pressure will be seen to be applied to chambers 28 and65, and the fit of piston 61 in bore 55, even though quite adequate forpumping oil, may be such that the pressurized air will seep past thesides of piston 61 into chamber 60, where the air, which is underpressure, will displace the fuel, which is at atmospheric or a very lowpressure, and shut off the engine, thereby preventing damage when theoil supply becomes entirely depleted.

FIGS. 3 and 3a through 311 illustrate a modified form of injector muchlike that of FIG. 2, but with certain differences which will be pointedout. Parts in FIGS. 3, 3a-3d generally similar to corresponding parts ofFIG.

2 are given similar numbers with a 1 prefix, e.g., piston 30 in FIG. 2corresponds to piston 130 in FIG. 3. As best seen in FIGS. 3 and 3d,pulley 124 driven from the crankshaft rotates shaft 123 which carriescam 127. Cam 127 reciprocates tappet 81, which is carried in bushing 82with an O-ring seal 83a. The right end of tappet 81 bears against theleft end of piston 130, which reciprocates within sleeve 129a. A spring133, only a portion of which is shown, is inserted between head 122 anda right-end face of piston 130 and operates to return piston 130. Alower gear sector 83 (FIGS. 3 and 3c) pinned to piston 130 is engaged byupper gear sector 84 pinned to control shaft 131, so that rotation ofshaft 131 angularly positions piston 130. Upper gear sector 84 isaxially wider than lower gear sector 83 so that the gears remainenmeshed as sector 83 reciprocates with piston 130. Oil is supplied tochamber 128 via a pipe connection made at 128a on the side of casting120. Oil and fuel inlet ports are provided in sleeve 129a at 134 and136, and oil and fuel outlet ports are shown at 135 and 137. Oil piston161 is urged rightwardly against head 122 by inner coil spring 162.Holes drilled in main (Part 120 at 142a and 147a connect the outletports with longitudinallyextending passages in which check valves 150and 151 are situated, and plugs 142e, 1476 close the ends of passages142 and 147a. Check valves 150 and 151 at the outlet side of theinjector are shown as comprising elastomeric or rubber duckbill valvesof a known type (Part No. VA 3178 of Material VL422 M2 sold by VernayLaboratories, Yellow Springs, Ohio), and each such valve connects withmixing chamber 143 provided in head 122.

Fuel chamber 164 in the device of FIG. 3 is shown provided with twoconnections 1450 and 145d (FIG. 3b) to the fuel tank 146 through twofurther duckbill check valves 90 and 91 (FIG. 3a) oriented in oppositedirections. If the injector pumping capacity is substantially greaterthan that required to run the engine at full speed under full load, asubstantial amount of fuel will oscillate in and out of fuel chamber 164as piston 130 reciprocates and the pressure in fuel chamber 164 risesand falls. This oscillation is rectified by duckbill valves 90 and 91,so that fuel is continuously drawn from fuel tank 146 into fuel chamber164 and continuously pumped from fuel chamber 164 out to fuel tank 146.The fuel tank acts as a heat sink, so that the continuous circulation offuel keeps the fuel cool at the injector and prevents the vapor lockwhich plagues many carburetor systems. It will be apparent at this pointthat a pair of oppositely-oriented check valves (not shown) also couldbe provided, if desired, to similarly connect oil chamber 128 to providecontinuous circulation of oil to and'from the oil tank.

FIG. 4 shows a modified mounting arrangement in which a portion of theinjector extends within an engine crankcase 114. The mountingarrangement shown in FIG. 4 was developed for use with acommerciallyavailable .ILO two-cycle engine Model TYT-L372L (Ser. No.37220305). Cam 227 carried eccentrically on the engine crankshaft 223 issurrounded by a nonrotatable porous bronze or oilite ring 85, which doesnot rotate, but which will be seen to be reciprocated with a planetarymotion as shaft 223 rotates eccentric cam 227. A hemisphericaldepression in ring is engaged by the hemispherical end of tappet 181,which is urged into engagement with ring 85 by the piston return spring(not shown in FIG. 4). Through use of ring 85 it will be seen thatmuchless sliding motion results between tappet 181 and ring 85 than wouldresult if tappet 181 directly engaged cam 227, and hence much less wearoccurs and any need to periodically adjust the length of tappet 181 orcompensate for a change in the length thereof is obviated. An oil hole86 in the injector opens into the engine crankcase and a passagewayleading therefrom carries oil to lubricate tappet 181. Aside from thedescribed manner in which its tappet is arranged to be reciprocated bythe engine, the injector pump of FIG. 4 otherwise corresponds with thepump of FIG. 3. While cam 227 in FIG. 4 must be circular in order to usering 85, it is important to note that cams 27 and 127 in FIGS. 2 and 3need not be circular, and can include various other shapes to providedesired reciprocating motion of the pistons which they drive.

FIGS. 5a and 5b illustrate the air intake duct and throttle platearrangement of one embodiment of the invention, and FIG. 6 illustratesthe manner in which injection nozzle assembly 18 extends into the engineintake duct. Air intake 15 includes a flange 15a which bolts to theengine adjacent the engine cylinder inlet port. A conventional circularthrottle plate is rotatably mounted on shaft 96 which extends throughduct 15, and shaft 96 is connected by any suitable arrangement to berotated by the vehicle accelerator pedal or throttle control, to openthrottle plate 95 when the engine is to be accelerated. Shaft 97 rigidlyaffixed to duct 15 and extending parallel to throttle-plate shaft 96carries pivot arm 98 and arm 99. Spring 100 affixed to duct urges arm 98clockwise as viewed in FIG. 5b, so that cam follower roller 101 carriedon arm 98 is urged against the periphery of rotatable throttle cam 102.As the accelerator pedal is depressed, throttleplate shaft 96 and cam102 are rotated counterclockwise as viewed in FIG. 5b, thereby rotatingarm 98 counterclockwise as the throttle plate unblocks the air intakeduct. The lower end of arm 98 connects, by means of an adjustableturnbuckle 103 to crank arm 104, and rightward movement of the lower endof arm 98 rotates the control rod of the fuel injector, rotating piston30 of FIG. 2 (or piston of FIG. 3) so as to increase the amount offuel-oil mixture pumped during each stroke. A wire 105 connected to arm99 leads to an engine choke control 96, a simple frictionpositionedknob. Pulling on control serves to rotate arm 98 counterclockwise aboutshaft 97, withdrawing cam follower roller 101 from cam 102, so that alarge amount of fuel-oil mixture may be supplied to the engine while thethrottle plate remains almost closed, thereby providing a rich mixturedesirable for starting a cold engine.

An alternative form of injector control suitable for use in variousindustrial engine applications wherein rapid acceleration is not asimportant as economy is shown in schematic form in FIG. 3e connected tothe injector of the type shown in FIG. 3, to provide an arrangementwherein the injector is controlled indirectly rather than directly withthe throttle plate opening. The engine crankcase scavenging pressure isapplied via check valve 106 and needle valve or orifice 107 to diaphragm108, and a bleed to atmosphere is provided through needle valve ororifice 109 from the diaphragm chamber. The scavenging pressure in theengine crankcase varies with throttle position and is a fairly accurateindication of the mass flow of air through the engine. The pressureapplied to diaphragm 108 will be seen to be proportional to peakscavenging pressure. The diaphragm is mechanically connected throughcrank arm 204 to rotate the injector control shaft 131 against the forceapplied to crank arm 204 by spring 110, the pressure of the spring beingadjustable by rotating threaded shaft 111 relative to fixed nut 112.Adjustment of spring 1 varies the richness of the air-oil-fuel mixtureapplied to the engine.

The mixing chamber of the injector connects through tubing 18a, which ispreferably very short, to the injector nozzle assembly best seen inFIGS. 6 and 6a. The injector nozzle assembly comprises a tube 215 havinga flared end which seats within an internal ring-shaped recess 216provided in the same type of duckbill check valve 218 as thosepreviously mentioned. A generally cylindrical insert 217 preferablyformed of solid hard nylon or the like extends forwardly out through thefront end of the elastomeric duckbill valve for a distance of aboutone-sixteenth inch, and when utilizing a Vernay Laboratories Model VA 3l 78 duckbill valve of the type mentioned, a nylon insert having adiameter of seven sixty-fourths inch has proven satisfactory. One insertsuitable for use with that model valve had dimensions shown in FIG. 6aas a through e of five thirtyseconds, one-sixteenth, sevensixty-fourths, fifteen thirty-seconds and one thirty-seconds inch,respectively. A portion of the insert within the valve is tapered downrearwardly to allow the mixture to completely surround the insert backfrom the exit end of the valve, and an enlarged tip 217a on the rear endof the insert also engages ring recess 216 to hold the insert securelywithin the valve. It will be apparent that the rear end of insert 217may be held in place by provision of suitable locking means on the endof tube 215 ifdesired. The essential feature of the nozzle assembly isthe provision in a flexible body having a fluid passageway of a centralbody having a substantially circular crosssection, so that the flexiblebody grips it on all sides with substantially uniform pressure, oversubstantially uniform area around the central body. The mixture pumpedby the injector completely surrounds insert 217 up to where the mouth offlexible valve 218 is stretched around the cylindrical insert. Becausevalve 218 is flexible and stretched around an insert which is circularin cross-section, it will be seen that the pressure with which theresilient valve grips the cylindrical insert will tend to be uniform allthe way around the insert, so that flow of the fuel-oil mixture willtend to occur evenly all the way around the valve, thereby providing athin ring-shaped spray" pattern. It will be noted that the spray patternwill remain ringshaped irrespective of the flow rate out of the nozzleassembly. Experience has shown that the provision of such a patternresults in very effective atomization of the mixture. The front endportion of the cylindrical insert gripped by the mouth of the duckbillvalve need not be truly cylindrical, but also may taper (preferablyenlarging outwardly). It is highly desirable, however, that that portionof the insert always be circular in cross-section.

The injection nozzle assembly will be seen to be extremely inexpensive,and reliable. Those skilled in the art will readily recognize that avariety of different elastomeric materials may be utilized to provideinjection nozzles, it being important, of course, that any suchmaterials not be adversely affected by exposure to oil or gasoline. Thediameter of the insert may be varied when different elastomericmaterials are used, of

course, to provide a desired tension of the valve mouth around thecylindrical insert, and hence to provide a desired pressure drop at thenozzle. While the tension around the ring-shaped nozzle mouth ordinarilywill need no adjustment, it will be apparent that an adjustable nozzlemay be made by provision of a taper on the nylon insert and provision ofadjusting means whereby the insert may be moved axially relative to theflexible encircling body. It will also be apparent that use of the newnozzle assembly is in no way restricted to twocycle fuel-oilatomization, but may be used in a wide variety of other applications,with many different fluids. Also, it will be apparent that the variousother features of the invention do not require the specific nozzleassembly shown and that numerous other types of nozzles may be utilized.

FIG. 7 illustrates an intake duct or manifold utilized with atwo-cylinder two-cycle engine wherein cylinders C-1 and C-2 operate outof phase, so that only one cylinder is aspirating at a given time. Theinjector nozzle 118 extends downwardly at a slant into the top of a Y-shaped duct 315 and points toward apex 315a of the duct. Each arm of theY-shaped duct leads to the input port associated with a respectivecylinder, and the common leg of the duct includes a throttle plate asimilar to plate 95 of FIG. 6 which controls air flow. The injector pump(not shown) which feeds nozzle 118 is arranged to operate at twice thespeed of a singlecylinder arrangement by halving the timing pulleydiameter or by providing two eccentric lobes on cam 27, for example.Running out of fuel or oil will be seen to disable both cylinders andstop the two-cylinder engine, obviating the damage which often occurs indual carburetor two-cylinder two-cycle engines if one carburetor becomesclogged or otherwise fails.

While I prefer to provide two separate tanks for fuel and oil to avoidrequirement for proper pre-mixing of the two fluids, it will be apparent:at this point that simplified versions of the injector pump having asingle V- groove and single inlet and outlet ports and a single outletcheck valve may be provided to pump a premixed mixture of fuel and oilfrom a single tank to an injection nozzle.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained, andsince certain changes may be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter containedin the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

The embodiments of the invention in which an exclusive property orprilege is claimed are defined as follows:

1. A fluid pump, comprising, ll'll combination: means defining acylindrical bore having an inlet port and an outlet port axially spacedfrom each other; a rotatablyadjustable piston adapted to reciprocatewithin said bore to decrease the size of a chamber formed by said pistonand said bore during a pumping stroke involving relative motion betweensaid piston and said bore for a predetermined distance in a firstdirection and to increase the size of said chamber during a returnstroke involving relative motion over said predetermined distance in anopposite direction, said piston having a passage adapted to connect saidchamber in a sequence of three successively different porting conditionsduring a pumping stroke throughout said predetermined distance, saidsequence consisting of a first porting condition during an initialportion of said pumping stroke in which said chamber is connected withsaid inlet port and not connected to said outlet port, a second portingcondition during an intermediate portion of said pumping stroke in whichsaid chamber is connected with both said ports, being connecteddecreasingly with said inlet port and increasingly with said outletport, and a third porting condition during a terminal portion of saidpumping stroke in which said chamber is connected with said outlet portand not connected to said inlet port, whereby delivery of fluid fromsaid outlet port may begin during said second porting condition,continue throughout said third porting condition, and further continuefor an initial portion of said return stroke, the rotation of saidpiston being operable to adjust the points during a pumping stroke atwhich said passage changes from a given one of said porting conditionsto a succeeding one of said porting conditions.

2. A fluid pump, comprising, in combination: means defining acylindrical bore having an inlet port and an outlet port axially spacedfrom each other; a rotatablyadjustable piston adapted to reciprocatewithin said bore commences, decrease the size of a chamber formed bysaid piston and said bore during a pumping stroke involving relativemotion between said piston and said bore in a first direction and toincrease the size of said chamber during a return stroke involvingrelative motion in an opposite direction, said piston having a passageadapted to connect said chamber in a sequence of successively differentporting conditions with only said inlet port during an initial portionof said pumping stroke, decreasingly with said inlet port andincreasingly with said outlet portduring an intermediate portion of saidpumping stroke during which delivery of fluid through said outlet portcommences, and with only said outlet port during a following terminalportion of said pumping stroke, the rotation of said piston beingoperable to adjust the points during said pumping stroke at which saidpassage changes from each one of said portingconditions to a succeedingone of said porting conditions, whereby delivery of fluid through saidoutlet port begins at a point determined by the rotary adjustment ofsaid piston and terminates at a piston position substantiallyindependent of said rotary adjustment of said piston.

3. A fluid pump, comprising, in combination: means defining acylindrical bore having an inlet port and an outlet port axially spacedfrom each other; a rotatablyadjustable piston adapted to reciprocatewithin said bore to decrease the size of a chamber formed by said pistonand said bore during a pumping stroke involving relative motion betweensaid piston and said bore in a first direction and to increase the sizeof said chamber during a return stroke involving relative motion in anopposite direction, said piston having a passage adapted to connect saidchamber in a sequence of successively different porting conditions withonly said inlet port during an initial portion of a pumping stroke and aterminal portion of a return stroke whereby fluid is expelled from saidchamber through said outlet port during said initial portion of saidpumping stroke, with both said ports during intermediate portions ofsaid pumping stroke and said return stroke, and with only said outletport during a terminal portion of said pumping stroke and an initialportion of said return stroke whereby fluid is expelled from saidchamber through said outlet port during said terminal portion of saidpumping stroke, the rotation of said piston being operable to adjust thepoints during said strokes at which said passage changes from each oneof said porting conditions to a succeeding one of said portingconditions.

4. A pump according to claim 3 wherein, with a given rotary adjustmentof said piston, said initial portion of said pumping stroke embraces thesame range of piston movement as said terminal portion of said returnstroke.

5. A pump according to claim 3 wherein, with a given rotary adjustmentof said piston, said intermediate portions of said pumping and returnstrokes embrace the same range of piston movement.

6. A pump according to claim 3 wherein, with a given rotary adjustmentof said piston, said terminal portion of said pumping stroke embracesthe same range of piston movement as said initial portion of said returnstroke.

7. A pump according to claim 3 having a first fluid supply sourceconnected to said inlet port; and an assembly including a second boreand a second piston adapted to decrease and increase the size of asecond chamber during said pumping and return strokes, respectively,second inlet and second outlet ports, said assembly having a passageadapted to connect said second chamber under said successively differentporting conditions with only said second inlet port, both said secondinlet port and said second outlet port, and with only said second outletport during said pumping stroke, the rotation of said piston carriedwithin said cylindrical bore being operable to adjust the points duringsaid pumping stroke at which said passage of said second piston changesfrom a given one of said porting conditions to a succeeding one of saidporting conditions; and a second fluid supply source connected to saidsecond inlet port.

8. A pump according to claim 7 having check valve means interconnectingsaid cylindrical bore and said second bore.

9. A pump according to claim 7 having a third chamber; said outlet portof said cylindrical bore being connected to said third chamber throughfirst check valve means and said second outlet port being connecte d tosaid third chamber through second check valve means, whereby fluidspumped from said first and second fluid supply sources are mixed in saidthird chamber.

10. A pump according to claim 7 wherein said first piston has aneffective area n times as great as the area of said second piston,whereby the amount of fluid pumped from said first fluid supply sourceis n times the amount of fluid pumped from said second fluid supplysource.

11. A pump according to claim 7 in which said second bore is locatedwithin said piston and said second inlet and outlet ports are spacedalong said cylindrical bore.

12. A pump according to claim 7 having valve means operable to spillfluid from said chamber formed by said piston and cylindrical bore; andmeans responsive to the pressure in said second bore for controllingsaid valve means.

13. A pump according to claim 7 having a greater pressure at said secondfluid supply source than at said first fluid supply source, wherebydepletion of fluid at said second supply source results in admission ofa gas or air to said cylindrical bore to displace the fluid therein andstop the pumping of the fluid supplied from said first fluid supplysource.

14. A pump according to claim 7 wherein said rotation of the pistonwithin said cylindrical bore is operabie to vary the amounts of fluidpumped from said first and second supply sources during a pumping strokewhile maintaining constant the ratio between said amounts. 15. A pumpaccording to claim 3 having check valve means connected to said outletport, whereby fluid may flow from said chamber through said outlet portand said check valve means only while said passage of said piston isconnected with both said ports or with only said outlet port, andwhereby suction will be built up in said chamber during a portion ofsaid return stroke.

16. A pump according to claim 3 having check valve means connected tosaid inlet port, whereby fluid may flow from said chamber through saidinlet port and said check valve means only while said passage of saidpistori is connected with both said ports or with only said inlet port,whereby fluid will be expelled from said chamber through said inlet portpast said check valve during said initial portion of a pumping stroke.

A pump according to claim 3 having a second fluid chamber connected tosaid inlet port; a fluid supply source, and first and secondoppositely-oriented check valve means each connected between said secondfluid chamber and said fluid supply source, said first check valve meansbeing operable upon increase in pressure in said second chamber during areturn stroke of said piston to return fluid from said second chambertoward said supply source, and said second check valve means beingoperable upon decrease of pressure in said second chamber during apumping stroke to admit fluid from said supply source toward said secondchamber, whereby reciprocation of said piston causes circulation offluid between said second chamber and supply source 1 8. In a fluid pumphaving piston means adapted to reciprocate within a cylindrical borehaving an inlet port and outlet means, said piston means having apassageway adapted to communicate with said inlet port during oneportion of a pumping stroke in which fluid is eitpelle'd from said borethrough said inlet port and adapted not to communicate with said inletport during a second portion of said pumping stroke during which fluidis expelled from said bore through said outlet means, said piston meansbeing angularly adjustable within said cylindrical bore to adjust therelative lengths of said two portions of said pumping stroke and therebyto adjust the amount of fluid pumped through said outlet means during apumping stroke, the combination of means defining a chambercommunicating with said piston means so that said piston means expandssaid chamber during said one portion of said pumping stroke, saidchamber being connected to communicate with said inlet port, wherebyexpansion of said chamber during said one portion of said pumping strokecreates a suction in said chamber to aid the expulsion of fluid fromsaid bore through said inlet port to said chamber during said oneportion of said pumping stroke.

19. A fluid pump, comprising, :in combination: a cylindrical bore havingan inlet port and an outlet port axially spaced from each other; arotatably-adjustable piston means adapted to reciprocate within saidbore to decrease the size of a first chamber formed by said bore andsaid piston means during a pumping stroke and to increase the size ofsaid chamber during a return stroke, said piston means having a passageadapted to connect said first chamber to said outlet port during oneportion of a return stroke and to connect said first chamber to saidinlet port during another portion of a return stroke; means defining asecond chamber adapted to be increased in size by said piston meansduring said pumping stroke and to be decreased in size during returnstroke; returnstroke; a fluid supply source; first and second checkvalve means; said second chamber being connected to said fluid supplysource through said first check valve means, said second chamber beingconnected to said inlet port, and said outlet port being connected tosaid second check valve means, whereby motion of said piston means during said one portion of said return stroke creates a pressure withinsaid second chamber and a suction between said inlet port and saidsecond check valve means, said pressure and suction acting cumulativelyduring said another portion of said return stroke to force fluid fromsaid second chamber through said inlet port into said first chamber.

20. A fluid pump, comprising, in combination: a first piston-cylinderassembly having a. first bore, a first piston adapted to reciprocatewithin said bore to vary the size of a first chamber formed by saidfirst piston and first bore during pumping and return strokes of fixedlength in opposite directions of said first piston relative to saidfirst bore, a first inlet port and a first outlet port, and a firstpassage reciprocable relative to said first inlet and outlet ports toconnect said first chamber sequentially to said first inlet port andsaid first outlet port; a second piston-cylinder assembly having asecond bore, a second piston adapted to reciprocate within said bore insynchronism with the reciprocation of said first piston within saidfirst bore to vary the size of a second chamber formed by said secondpiston and said second bore, a second inlet port and a second out letport, and a second passage reciprocable relative to said second inletand outlet ports: to connect said second chamber sequentially to saidsecond inlet port and second outlet port; means for connecting a firstfluid supply source to said first inlet port; means for connecting asecond fluid supply source to said second inlet port; and means forrotating said first passage relative to said first inlet port and saidfirst outlet port and rotating said second passage relative to saidsecond inlet port and said second outlet port to vary the points duringsaid pumping and return strokes at which said first passage connects tosaid first inlet port and said first outlet port and at which saidsecond passage connects to said second inlet port and said second outletport, thereby to vary the amounts of fluids pumped from said first andsecond-supply sources.

1. A fluid pump, comprising, in combination: means definiNg acylindrical bore having an inlet port and an outlet port axially spacedfrom each other; a rotatably-adjustable piston adapted to reciprocatewithin said bore to decrease the size of a chamber formed by said pistonand said bore during a pumping stroke involving relative motion betweensaid piston and said bore for a predetermined distance in a firstdirection and to increase the size of said chamber during a returnstroke involving relative motion over said predetermined distance in anopposite direction, said piston having a passage adapted to connect saidchamber in a sequence of three successively different porting conditionsduring a pumping stroke throughout said predetermined distance, saidsequence consisting of a first porting condition during an initialportion of said pumping stroke in which said chamber is connected withsaid inlet port and not connected to said outlet port, a second portingcondition during an intermediate portion of said pumping stroke in whichsaid chamber is connected with both said ports, being connecteddecreasingly with said inlet port and increasingly with said outletport, and a third porting condition during a terminal portion of saidpumping stroke in which said chamber is connected with said outlet portand not connected to said inlet port, whereby delivery of fluid fromsaid outlet port may begin during said second porting condition,continue throughout said third porting condition, and further continuefor an initial portion of said return stroke, the rotation of saidpiston being operable to adjust the points during a pumping stroke atwhich said passage changes from a given one of said porting conditionsto a succeeding one of said porting conditions.
 2. A fluid pump,comprising, in combination: means defining a cylindrical bore having aninlet port and an outlet port axially spaced from each other; arotatably-adjustable piston adapted to reciprocate within said borecommences, decrease the size of a chamber formed by said piston and saidbore during a pumping stroke involving relative motion between saidpiston and said bore in a first direction and to increase the size ofsaid chamber during a return stroke involving relative motion in anopposite direction, said piston having a passage adapted to connect saidchamber in a sequence of successively different porting conditions withonly said inlet port during an initial portion of said pumping stroke,decreasingly with said inlet port and increasingly with said outlet portduring an intermediate portion of said pumping stroke during whichdelivery of fluid through said outlet port commences, and with only saidoutlet port during a following terminal portion of said pumping stroke,the rotation of said piston being operable to adjust the points duringsaid pumping stroke at which said passage changes from each one of saidportingconditions to a succeeding one of said porting conditions,whereby delivery of fluid through said outlet port begins at a pointdetermined by the rotary adjustment of said piston and terminates at apiston position substantially independent of said rotary adjustment ofsaid piston.
 3. A fluid pump, comprising, in combination: means defininga cylindrical bore having an inlet port and an outlet port axiallyspaced from each other; a rotatably-adjustable piston adapted toreciprocate within said bore to decrease the size of a chamber formed bysaid piston and said bore during a pumping stroke involving relativemotion between said piston and said bore in a first direction and toincrease the size of said chamber during a return stroke involvingrelative motion in an opposite direction, said piston having a passageadapted to connect said chamber in a sequence of successively differentporting conditions with only said inlet port during an initial portionof a pumping stroke and a terminal portion of a return stroke wherebyfluid is expelled from said chamber through said outlet port during saidinitial portion of said pumping stroke, with both said portS duringintermediate portions of said pumping stroke and said return stroke, andwith only said outlet port during a terminal portion of said pumpingstroke and an initial portion of said return stroke whereby fluid isexpelled from said chamber through said outlet port during said terminalportion of said pumping stroke, the rotation of said piston beingoperable to adjust the points during said strokes at which said passagechanges from each one of said porting conditions to a succeeding one ofsaid porting conditions.
 4. A pump according to claim 3 wherein, with agiven rotary adjustment of said piston, said initial portion of saidpumping stroke embraces the same range of piston movement as saidterminal portion of said return stroke.
 5. A pump according to claim 3wherein, with a given rotary adjustment of said piston, saidintermediate portions of said pumping and return strokes embrace thesame range of piston movement.
 6. A pump according to claim 3 wherein,with a given rotary adjustment of said piston, said terminal portion ofsaid pumping stroke embraces the same range of piston movement as saidinitial portion of said return stroke.
 7. A pump according to claim 3having a first fluid supply source connected to said inlet port; and anassembly including a second bore and a second piston adapted to decreaseand increase the size of a second chamber during said pumping and returnstrokes, respectively, second inlet and second outlet ports, saidassembly having a passage adapted to connect said second chamber undersaid successively different porting conditions with only said secondinlet port, both said second inlet port and said second outlet port, andwith only said second outlet port during said pumping stroke, therotation of said piston carried within said cylindrical bore beingoperable to adjust the points during said pumping stroke at which saidpassage of said second piston changes from a given one of said portingconditions to a succeeding one of said porting conditions; and a secondfluid supply source connected to said second inlet port.
 8. A pumpaccording to claim 7 having check valve means interconnecting saidcylindrical bore and said second bore.
 9. A pump according to claim 7having a third chamber; said outlet port of said cylindrical bore beingconnected to said third chamber through first check valve means and saidsecond outlet port being connecte d to said third chamber through secondcheck valve means, whereby fluids pumped from said first and secondfluid supply sources are mixed in said third chamber.
 10. A pumpaccording to claim 7 wherein said first piston has an effective area ntimes as great as the area of said second piston, whereby the amount offluid pumped from said first fluid supply source is n times the amountof fluid pumped from said second fluid supply source.
 11. A pumpaccording to claim 7 in which said second bore is located within saidpiston and said second inlet and outlet ports are spaced along saidcylindrical bore.
 12. A pump according to claim 7 having valve meansoperable to spill fluid from said chamber formed by said piston andcylindrical bore; and means responsive to the pressure in said secondbore for controlling said valve means.
 13. A pump according to claim 7having a greater pressure at said second fluid supply source than atsaid first fluid supply source, whereby depletion of fluid at saidsecond supply source results in admission of a gas or air to saidcylindrical bore to displace the fluid therein and stop the pumping ofthe fluid supplied from said first fluid supply source.
 14. A pumpaccording to claim 7 wherein said rotation of the piston within saidcylindrical bore is operable to vary the amounts of fluid pumped fromsaid first and second supply sources during a pumping stroke whilemaintaining constant the ratio between said amounts.
 15. A pumpaccording to claim 3 having check valve means connected to said outletport, whereby fluid may flow frOm said chamber through said outlet portand said check valve means only while said passage of said piston isconnected with both said ports or with only said outlet port, andwhereby suction will be built up in said chamber during a portion ofsaid return stroke.
 16. A pump according to claim 3 having check valvemeans connected to said inlet port, whereby fluid may flow from saidchamber through said inlet port and said check valve means only whilesaid passage of said piston is connected with both said ports or withonly said inlet port, whereby fluid will be expelled from said chamberthrough said inlet port past said check valve during said initialportion of a pumping stroke. A pump according to claim 3 having a secondfluid chamber connected to said inlet port; a fluid supply source, andfirst and second oppositely-oriented check valve means each connectedbetween said second fluid chamber and said fluid supply source, saidfirst check valve means being operable upon increase in pressure in saidsecond chamber during a return stroke of said piston to return fluidfrom said second chamber toward said supply source, and said secondcheck valve means being operable upon decrease of pressure in saidsecond chamber during a pumping stroke to admit fluid from said supplysource toward said second chamber, whereby reciprocation of said pistoncauses circulation of fluid between said second chamber and supplysource
 18. In a fluid pump having piston means adapted to reciprocatewithin a cylindrical bore having an inlet port and outlet means, saidpiston means having a passageway adapted to communicate with said inletport during one portion of a pumping stroke in which fluid is expelledfrom said bore through said inlet port and adapted not to communicatewith said inlet port during a second portion of said pumping strokeduring which fluid is expelled from said bore through said outlet means,said piston means being angularly adjustable within said cylindricalbore to adjust the relative lengths of said two portions of said pumpingstroke and thereby to adjust the amount of fluid pumped through saidoutlet means during a pumping stroke, the combination of means defininga chamber communicating with said piston means so that said piston meansexpands said chamber during said one portion of said pumping stroke,said chamber being connected to communicate with said inlet port,whereby expansion of said chamber during said one portion of saidpumping stroke creates a suction in said chamber to aid the expulsion offluid from said bore through said inlet port to said chamber during saidone portion of said pumping stroke.
 19. A fluid pump, comprising, incombination: a cylindrical bore having an inlet port and an outlet portaxially spaced from each other; a rotatably-adjustable piston meansadapted to reciprocate within said bore to decrease the size of a firstchamber formed by said bore and said piston means during a pumpingstroke and to increase the size of said chamber during a return stroke,said piston means having a passage adapted to connect said first chamberto said outlet port during one portion of a return stroke and to connectsaid first chamber to said inlet port during another portion of a returnstroke; means defining a second chamber adapted to be increased in sizeby said piston means during said pumping stroke and to be decreased insize during return stroke; returnstroke; a fluid supply source; firstand second check valve means; said second chamber being connected tosaid fluid supply source through said first check valve means, saidsecond chamber being connected to said inlet port, and said outlet portbeing connected to said second check valve means, whereby motion of saidpiston means during said one portion of said return stroke creates apressure within said second chamber and a suction between said inletport and said second check valve means, said pressure and suction actingcumulatively during said another portion of said return stroke to fOrcefluid from said second chamber through said inlet port into said firstchamber.
 20. A fluid pump, comprising, in combination: a firstpiston-cylinder assembly having a first bore, a first piston adapted toreciprocate within said bore to vary the size of a first chamber formedby said first piston and first bore during pumping and return strokes offixed length in opposite directions of said first piston relative tosaid first bore, a first inlet port and a first outlet port, and a firstpassage reciprocable relative to said first inlet and outlet ports toconnect said first chamber sequentially to said first inlet port andsaid first outlet port; a second piston-cylinder assembly having asecond bore, a second piston adapted to reciprocate within said bore insynchronism with the reciprocation of said first piston within saidfirst bore to vary the size of a second chamber formed by said secondpiston and said second bore, a second inlet port and a second outletport, and a second passage reciprocable relative to said second inletand outlet ports to connect said second chamber sequentially to saidsecond inlet port and second outlet port; means for connecting a firstfluid supply source to said first inlet port; means for connecting asecond fluid supply source to said second inlet port; and means forrotating said first passage relative to said first inlet port and saidfirst outlet port and rotating said second passage relative to saidsecond inlet port and said second outlet port to vary the points duringsaid pumping and return strokes at which said first passage connects tosaid first inlet port and said first outlet port and at which saidsecond passage connects to said second inlet port and said second outletport, thereby to vary the amounts of fluids pumped from said first andsecond-supply sources.
 21. A pump according to claim 20 in which theangular positional relationship of said first passage relative to saidfirst inlet port and first outlet port differs from the angularpositional relationship of said second passage relative to said secondinlet port and second outlet port, whereby rotation of said passagesrelative to said ports varies the ratio between the amounts of thefluids pumped from said first and second fluid supply.
 22. A pumpaccording to claim 20 in which said first and second outlet ports areconnected through first and second check valve means, respectively, to amixing chamber.
 23. A fluid pump, comprising, in combination: firstcylinder means having a first bore; first piston means adapted toreciprocate within said first bore and vary the size of a first chamberformed by said first piston and said first bore; second cylinder meansdefining a cylindrical second bore, said first cylinder means having acylindrical cross-section and being adapted to reciprocate as a pistonwithin said second cylinder means to vary the size of a second chamber,said second cylinder means including a first inlet port and a firstoutlet port axially spaced from each other along said second cylindermeans, said first cylinder means having a first passage adapted toconnect said first chamber sequentially with said first inlet and outletports, said second cylinder means including a second input port and asecond outlet port, said first cylinder means having a second passageadapted to connect said second chamber sequentially with said secondinlet and outlet ports.
 24. A pump according to claim 23 having meansfor reciprocating said first cylinder means through a fixed distancerelative to said first piston and said second cylinder means; and meansfor rotating said first cylinder means relative to said second cylindermeans to vary the proportionate parts of said distance at which saidfirst and second passages connect with inlet ports and outlet ports.